Modeling the Effect of BEB for a Hidden Terminal Topology from a New Perspective [invited]

Athanasia Tsertou (University of Edinburgh, UK); David I. Laurenson, (University of Edinburgh, UK)

The last couple of years were characterised by the revival of interest in the performance evaluation of wireless multihop networks. An issue of great significance in carrier-sense based multihop networks is the hidden node problem. In our recent work we showed that previous techniques are suitable for limited node configurations and we proposed a novel time model that relaxes most assumptions in the literature and exhibits high accuracy of performance evaluation. The present paper extends our recent work, which was based on a constant contention window assumption, to the Binary Exponential Backoff (BEB) mechanism of IEEE 802.11, with an equally high degree of agreement to simulation results. Key points of our analysis are the consideration of different collision probabilities, dependent on the backoff stage, and the use of a Discrete Time Markov Chain embedded in the channel state evolution that allows us to compute the `backoff-dwelling' distribution of each transmitter.

Analysis of Co-existence between IEEE 802.11 and IEEE 802.16 Systems

Nicholas Thomas (Rutherford Appleton Laboratory, UK); Michael Willis (CCLRC Rutherford Appleton Laboratory, UK); Ken Craig (CCLRC, UK)

Both IEEE 802.11 and IEEE 802.16 standards have become widespread throughout the world in license-exempt spectrum specifically in the 5GHz band. However there is a problem in that the two standards are not designed to co-exist in close proximity together on the same or overlapping channels. In this paper an initial analysis of the performance degradation for co-existing IEEE 802.11 and IEEE 802.16 systems is presented.  Analysis is carried out at the medium access control (MAC) layer by means of an event model based simulation tool. The results show that in co-existence scenarios the performance of both systems will degrade severely and as a result spectrum efficiency can drop to close to zero.

On-Demand Connection-Oriented Multi-Channel MAC Protocol for Ad-Hoc Network

Peng-Jung Wu (National Sun-Yat Sen University of Taiwan, TW); Chung-Nan Lee (University of Yat-sen, TW)

This paper presents an on-demand connection-oriented multi-channel MAC protocol for Ad-Hoc networks. The major characteristics of proposed protocol are: (a) each mobile node is equipped with two network interfaces, (b) frame broadcasting is supported and (c) no time synchronization is needed. Compared with other multi-channel MAC protocols, the proposed protocol reduces the cost of channel negotiation by considering the property that a connection generates multiple frames for transmitting. NS-2 is used to evaluate the performance of the proposed protocol. Simulation results show that the proposed protocol can reduce the cost of channel negotiation and increase the network throughput.

Novel Sensor MAC Protocol Applied to Cayley and Manhattan

Eric Noel (AT&T Laboratories Research, US); Wendy Tang (SUNY Stony Brook, US)

With the rapid growth of wireless sensor technology, we foresee a need for MAC protocols to allow efficient simultaneous peer-to-peer communications in large and dense wireless sensor networks. To meet such a need, we propose a novel MAC protocol that exploits network graphs property to assign frequencies such that the number of intermediate hops to reach destinations is minimized. Via a simulation model parameterized to CrossBow MICA2, we evaluate the performance of our MAC protocol with Cayley and Manhattan Street networks.

Link Cost and Reliability of Frame Preamble MAC Protocols

Abdelmalik Bachir (France Telecom & IMAG, France); Ludovic Samper (France Telecom & Verimag, France); Dominique Barthel (France Telecom, FR); Martin Heusse (LSR-IMAG, FR);  Andrzej Duda (LSR-IMAG, FR)

Previous studies have shown that preamble MAC protocols have higher energy efficiency compared to traditional low power MAC protocols based on common sleep/wakeup schedules. One efficient implementation of preamble MAC protocols is Frame Preamble MAC in which the MAC preamble is replaced by a series of frames. In this paper, we consider four Frame Preamble MAC protocols, namely: persistent MFP (Micro Frame Preamble), non persistent MFP, persistent DFP (Data Frame Preamble), and non persistent DFP. We study their energy cost and communication reliability by assuming a simple binary symmetric channel error model.

1-hopMAC: An Energy-Efficient MAC Protocol for Avoiding 1-hop Neighborhood Knowledge

Thomas Watteyne (France Telecom & INSA Lyon, France); Abdelmalik Bachir; Mischa Dohler; Dominique Barthel; Isabelle Augé-Blum (INSA Lyon, France)

Wireless Sensor Networks (WSNs) have witnessed a tremendous upsurge in recent years, both in academia and industry; this is mainly attributed to their unprecedented operating conditions and a variety of commercially viable applications. Because of their dependence on scarce battery power, communication protocols need to be energy efficient. However, finding the optimal solution is challenging as it needs to consider the whole communication stack at once. In this paper, we propose an approach that aims at optimizing jointly L2 (link) and L3 (routing) protocols. We design 1-hopMAC, a communication architecture grouping MAC and routing layers which avoids 1-hop neighborhood knowledge. 1-hopMAC can be combined, among others, with a geographic or gradient based routing protocols. We present an analytical study of energy consumption to point out the optimal configuration of 1-hopMAC.

Sensor Networks with Decentralized Binary Detection: Clustering and Lifetime

Gianluigi Ferrari (University of Parma, IT); Marco Martalò (University of Parma, IT)

In this paper, we analyze the lifetime of clustered sensor networks with decentralized binary detection under a physical layer quality of service (QoS) constraint, given by the maximum tolerable probability of decision error at the access point (AP). In order to properly model the network behavior, we consider four different distributions (exponential, uniform, Rayleigh, and lognormal) for the lifetime of a single sensor. We show the benefits, in terms of longer network lifetime, of adaptive reclustering. On the other hand, absence of reclustering leads to a shorter network lifetime, and we show the impact of various clustering configurations under different QoS conditions. Our results show that the organization of sensors in a few big clusters is the winning strategy to maximize the network lifetime.

Scalable Coverage Maintenance for Dense Wireless Sensor Networks

Jun Lu (University of California, Irvine, US); Jinsu Wang (University of California, Irvine, US); Tatsuya Suda (University of California, Irvine, US)

Owing to numerous potential applications, wireless sensor networks have been attracting much research effort recently. The critical challenge that wireless sensor networks often face is to sustain long-term operation on limited battery energy. Coverage maintenance schemes can effectively prolong

network lifetime by maintaining sufficient sensing coverage over a target region using a small number of active sensors while scheduling the other sensors to sleep. We envision that future wireless sensor networks will be composed of a vast amount of extremely miniaturized sensors (e.g., millimeter-scale) with limited processing capability and storage capacity, deployed in exceedingly high density (e.g., more than 1000 sensors/m2). Therefore, the key issue of coverage maintenance for the future sensor networks is the scalability to sensor deployment density. In this paper, we propose a novel coverage maintenance scheme, called Scalable COverage Maintenance (SCOM). SCOM is energy efficient and scalable to sensor deployment density in terms of communication overhead (i.e., number of transmitted and received beacons) and computational complexity (i.e., time and space complexity). We validate our claims through both theoretical analysis and simulations.

Clustering and Wireless Sensor Networks: A Paradigm Shift?

Thomas Watteyne (France Telecom & INSA Lyon, France); Isabelle Augé-Blum (INSA Lyon, France)

not available

Dynamic Local Clustering for Hierarchical Ad Hoc Networks

Satu Elisa Schaeffer (Helsinki University of Technology, FI); Stefano Marinoni (Helsinki University of Technology, FI); Mikko Särelä (Helsinki University of Technology, FI); Pekka Nikander (Ericsson Research Nomadiclab, FI)

Hierarchical, cluster-based routing greatly reduces routing table sizes compared to host-based routing, while reducing path efficiency by at most a constant factor [9]. More importantly, the amount of routing related signalling traffic is reduced [7, 11, 19]. On the other hand, address changes caused by nodes changing their cluster produces address management traffic. In this paper, we present a new local clustering method that produces dense and stable clusters, thereby minimizing address changes and allowing better and more stable network conditions for ad hoc routing.

A Distributed Min-Max Tree Algorithm for Scalable Maximum-Lifetime Multicast in Resource-limited Wireless Ad Hoc Networks  [invited]

Song Guo (University of British Columbia, Canada); Victor Leung (University of British Columbia, Canada)

We consider the problem of maximizing the multicast lifetime in multihop wireless networks in which each node is static and has limited energy, bandwidth, memory, and computation capabilities. Unlike most multicast algorithms that use centralized greedy algorithms, our algorithm can construct a global optimal maximum lifetime multicast tree in a distributed manner. It has a low complexity of O(λu) for both memory and computation requirements at each node u, where λu is the degree of node u. The simulation results have shown that it has an expected linear communication complexity under different network sizes and multicast group sizes. This means that our distributed algorithm is also scalable in terms of communication overhead and it is very useful for large-scale energy and bandwidth constrained multihop wireless networks like sensor networks.

Ubiquitous Zone (u-Zone) based Community Networking Technologies

Yun Won Chung (Soongsil University, KR); Namhi Kang (Soongsil University, KR); Younghan Kim (Soongsil University, KR)

This work introduces ubiquitous zone (u-Zone) based community networking technologies project aimed at providing ubiquitous computing environment for community networking. A u-Zone network architecture with ubiquitous zone master (u-ZM), which manages u-Zone, is proposed. These u-ZMs form a mesh network via wireless backbone (WBB). Thus, u-Zone network can be considered as a hybrid network of MANET between u-ZM and nodes and mesh network between u-ZMs. Either proactive or reactive routing protocol can be used in intra-zone routing and inter-zone routing in the u-Zone network. Thus, four routing modes are proposed and the detailed operations of them are illustrated. Then, the pros and cons of the four routing modes are discussed. Also, the proposed u-Zone network supports routing between nodes operating with heterogeneous routing protocols in the same u-Zone by heterogeneous routing protocol coordinator (HRPC). Our u-Zone network with u-ZMs will serve as a new network infrastructure for future community networking for ubiquitous computing.

Waveform Design and Diversity in Radar Sensor Networks: Theoretical Analysis and Application to Automatic Target Recognition

Qilian Liang (University of Texas at Arlington, US)

In this paper, we perform some theoretical studies on constant frequency (CF) pulse waveform design and diversity in radar sensor networks (RSN): (1) the conditions for waveform co-existence, (2) interferences among waveforms in RSN, (3) waveform diversity combining in RSN. As an application example, we apply the waveform design and diversity to automatic target recognition (ATR) in RSN and propose maximum-likehood (ML)-ATR algorithms for nonfluctuating target as well as fluctuating target. Simulation results show that our waveform diversity-based ML-ATR algorithm performs much better than single-waveform MLATR algorithm for nonfluctuating targets or fluctuating targets. Conclusions are drawn based on our analysis and simulations.

Distributed timing synchronization for sensor networks with coupled discrete-time oscillators

Osvaldo Simeone (Politecnico di Milano, IT)

Physical layer-based distributed timing synchronization among nodes of a wireless network is currently being investigated in the literature as an interesting alternative to packet synchronization. In this paper, we analyze the convergence properties of such a system through algebraic graph theory, by modelling the nodes as discrete-time oscillators and taking into account the specific features of wireless channels (e.g., reciprocity, fading). The analysis is corroborated by numerical results and by comparison with the performance of a practical implementation of the distributed synchronization algorithm over a bandlimited noisy channel.

The Energy-per-Useful-Bit Metric for Evaluating and Optimizing Sensor Network Physical Layers

Josephine Ammer (University of Washington, US); Jan Rabaey (UC Berkeley, US)

To become truly ubiquitous, sensor network nodes must achieve ultra low power consumption. This paper proposes the Energy-per-Useful-Bit (EPUB) metric for evaluating and comparing sensor network physical layers. EPUB includes the energy consumption of both the transmitter and receiver, and amortizes the energy consumption during the synchronization preamble over the number of data bits in the packet. Using EPUB, we compare six existing sensor network PHYs. Next, we optimize the PHY according to EPUB. We conclude that the EPUB of sensor network PHYs can be reduced by increasing data rate, lowering carrier frequency, and using simple modulation schemes such as OOK to reduce synchronization overhead.

Multichannel Feedback in OFDM Ad Hoc Networks

Taiwen Tang (The University of Texas, Austin, US); Ketan Mandke (The University of Texas at Austin, US); Chan-Byoung Chae (The University of Texas, Austin, US); Robert Heath (The University of Texas at Austin, US); Scott Nettles (University of Texas at Austin, US)

We propose a multichannel feedback protocol to enable local scheduling with channel state information for wireless networks with orthogonal frequency division multiplexing (OFDM). In our proposed protocol, the frequency subcarrier domain is shared by multiple control channels, on which request-to-send (RTS) and clear-to-send (CTS) are exchanged. These control channels are created using random spreading signatures. Channel state information of the simultaneous transmissions, which defines the gains of these channels, is exchanged on these control channels and channel state information tables that contain the channel information of both the desired link and the interfering links are created at the transmit nodes, then scheduling decisions are made based on the channel information tables. We show that the proposed protocol improves the network throughput compared to IEEE 802.11 style protocols for a wireless local area network topology.

Eavesdropping Minimization via Transmission Power Control in Ad-Hoc Wireless Networks

Jung-Chun Kao (Carnegie Mellon University, US)

Reconnaissance activity is the most frequent incident on computer networks since 2002. In fact, most attacks (including DoS attacks) are usually preceded by reconnaissance activity. In order to defend against reconnaissance activity in ad-hoc wireless networks, we propose to use transmission power control as an effective mean to minimize the eavesdropping risk. Our main contributions are as follows: First, we cast the w-th order eavesdropping risk as the maximum probability of packets being eavesdropped when there are w adversarial nodes in the network. Second, we derive the closed-form solution of the 1^st order eavesdropping risk as a 3rd-order polynomial function of normalized transmission radius. This derivation is based on the recently proposed model by El Gamal which assumes a uniform distribution of user nodes. Then we generalize the model to allow arbitrary user nodes distribution and prove that the uniform user distribution actually minimizes the 1st order eavesdropping risk. This result plays an essential role in deriving the first analytical bounds for the eavesdropping risk given arbitrary user distribution. Our simulation results show that for a wide range of non-uniform traffic patterns, the eavesdropping risk has the same order of magnitude as the corresponding uniform traffic cases.

Elements of PHY/MAC Cross-Layer Optimisation for CSMA-based Ad Hoc Networks

Mischa Dohler (France Telecom, FR); Athanasios Gkelias (King's College London, UK); A. Hamid Aghvami (King's College London, UK)

We investigate the impact of power control and choice of modulation index on the performance of a multi hop CSMA/CA system. We explicitly take into account the additional traffic generated due to multi-hop transmissions and the effect of frame error rates, the later being a function of the frame length, the modulation index, and the signal-to-noise ratio (SNR). An analytical model for the spectral throughput per user is presented with emphasis on the number of nodes dwelling in the area covered by a given transmission power and on the number of hops. Unlike other works, a closed form solution is derived for the spectral throughput performance of a multi hop CSMA/CA system as a function of the offered load, the nodes density, transmission power and frame error rate. This facilitates the PHY and MAC layers to be jointly optimised, e.g. the system designer may specify the optimum choice of modulation index for a given MAC configuration or, alternatively, the optimum persistency parameter for a given PHY.

A Communication-Theoretic Approach to Ad Hoc Wireless Networking [invited]

Ozan K. Tonguz (Carnegie Mellon University, USA); Gianluigi Ferrari (University of Parma, Italy)

The remarkable surge in research on ad hoc wireless networks is largely due to their potential in offering insfrastructureless communications. While initially studied adopting a “conventional” networking approach, based upon years of research experience on wired computer networks (with virtually error-free communication links), the presence of unreliable wireless communication links necessitates a communication-theoretic foundation for the design and analysis of wireless ad hoc networks. Such a novel comprehensive “bottom-up” perspective was, for the first time, presented in [1]. In this paper, we summarize the communication-theoretic framework of [1], where the impact of physical layer on the network performance and its interaction with higher layers is taken into account. The main goal of this paper is to provide the reader with the intuition behind the comprehensive approach presented in [1], rather than the mathematical details of the approach.

Emulation Architecture Implementation and Design

Alessandra Giovanardi (University of Ferrara, IT); Gianluca Mazzini (University of Ferrara, IT)

The design and implementation of an emulation architecture for ad hoc networks is described in details and tested. The tool is able to emulate many unicast routing protocols with a real exchange of signaling and data packets between the hosts present in the network. With respect to a wireless test bed, the emulator works on hosts connected each other via wired links and the wireless channel is simulated. The emulator works in the user space, and allows an easy interface with the Simple Ad hoc siMulator (SAM) [1], where many routing protocols are present.

A Low Cost and Flexible Network Testbed

Federico Fergnani (University of Ferrara, IT); Gianluca Mazzini (University of Ferrara, IT)

New network technologies and services encourage the search for new networking ideas and new protocols; the main problem that we encounter developing this ideas is to test the result of our work in a realistic test environment. In this paper we describe how it is possible to build a low cost network testbed, easy to modify and based on the integration of open source software. Beside we show, as an example, a practical implementation of such a testbed and some tests performed about improving packet transmission reliability using different redundant transmission techniques. We identified two different techniques of redundant transmission on an IP network and we performed some transmission tests emulating situations of network malfunctioning that proof how the use of redundant transmission permits to strongly reduce the effects of network problems.

A Biologically Inspired Architecture for Self-Managing Sensor Networks

Pruet Boonma (University of Massachusetts, Boston, US); Paskorn Champrasert (University of Massachusetts, US); Junichi Suzuki (University of Massachusetts, Boston, US)

This paper describes a sensor network architecture, called BiSNET, which addresses several key issues in wireless sensor networks such as autonomy, adaptability and self-healing. Based on the observation that various biological systems have developed mechanisms necessary to overcome these issues, BiSNET follows certain biological principles such as decentralization, food gathering/storage and natural selection to design sensor networks. This paper describes and evaluates the biologically-inspired mechanisms in BiSNET. Preliminary simulation results show that BiSNET allows sensor nodes to autonomously adapt their duty cycles for power efficiency and responsiveness of data transmission and to collectively self-heal (i.e., detect and eliminate) false positives in their sensor readings.

An Internet SIP Gateway for Ad-hoc Networks

Jukka Manner (Helsinki University of Technology, FI); Kimmo Raatikainen (University of Helsinki, FI); Simone Leggio (Open Source Software Operations, Nokia Multimedia, FI)

Various forms of ad-hoc networking are slowly emerging. However, a wider diffusion of ad-hoc networking in everyday life will only be possible if existing common applications are adapted for use in ad-hoc networks. There has been some work on adapting Internet-based applications to function in adhoc networks. Yet, in order to make ad-hoc networking even more useful and interesting to people, applications must also be able to connect to the Internet. Many new Internet applications are based on sessions, e.g., instant messaging, VoIP and multimedia communications. The Session Initiation Protocol (SIP) is a popular protocol to manage sessions in IP networks, based on centralized servers, and application-level routing. However, in order to establish SIP sessions between an ad-hoc network and the Internet, some logic must be built in the ad-hoc gateway node to make messages flow correctly to and from the ad-hoc network. In this paper, we present an intelligent SIP gateway that makes it possible to route messages properly between ad-hoc networks, and the Internet, even when the ad-hoc IP addresses are not globally routable.

Bandwidth Consumption for Providing Fair Internet Access in Wireless Mesh Networks

Thomas Scherer (University of Luxembourg, LU); Thomas Engel (University of Luxemburg, LU)

The contribution of this work is to examine the performance of WMNs concerning bandwidth. Here, we provide a lower bound for bandwidth utilization in mesh networks. We analyze how much bandwidth may be provided to all mesh nodes if they communicate over one wireless communication channel and use the same gateway to the internet. Even in such a scenario where devices compete on the access to the wireless channel it is possible to operate without bandwidth loss and share this bandwidth uniformly over the set of mesh nodes. This is achievable by optimizing spatial reuse. Here, this is achieved by scheduling channel access using time slots. Of course, this is not possible for every network topology. We measure the fraction of topologies that may operate with a uniformly shared maximum bandwidth.

Modeling End-to-end Distance for Given Number of Hops in Wireless Sensor Networks

Liang Zhao (University of Texas at Arlington, US); Qilian Liang (University of Texas at Arlington, US)

We model the end-to-end distance for a given number of hops in dense planar Wireless Sensor Networks in this paper. We derive that the closed-form formula for singlehop distance and postulate Beta distribution for 2-hop distance. When the number of hops increases beyond three, the multihop distance approaches Gaussian. The Gaussian approximation model is also applied to ranging, which achieves less distance error than Hop-TERRAIN and APS (Ad hoc Positioning System). Our error analysis also shows the distance error is be minimized by using our model.

Mathematical Analysis of Tree-Based Topologies for Multi-Sink Wireless Sensor Networks

John Orriss (Department of Computer Science, University of Manchester, UK); Roberto Verdone (University of Bologna, IT)

This paper investigates the design of tree-based topologies for multi-sink Wireless Sensor Networks (WSNs). A mathematical framework is used to optimise the maximum number of levels in the trees as a trade-off between energy conservation needs and requirements related to the minimum number of samples that need to be received by sinks. A capacity limit in terms of maximum number of children per parent is included in the evaluations. Path loss, random channel fluctuations, sink and sensor node densities, random locations, are considered through a statistical study that also allows the evaluation of the impact of a retry mechanism when forming the trees.

A Statistical Model for the Evaluation of the Distribution of the Received power in ad Hoc and Wireless Sensor Networks

Alberto Zanella (CSITE-CNR, DEIS, University of Bologna, IT); Enrica Salbaroli (University of Bologna, IT)

In this paper we consider a scenario composed by nodes which are uniformly and randomly distributed in a given area and derive the distribution of the power received by a given terminal. The model, which takes a propagation environment characterized by distance-dependent loss and lognormally distributed shadowing into account, can be used to evaluate the distribution of the received power in wireless ad hoc and sensor networks. In particular, the model is suited to investigate the distribution of the received useful and the interference power in a scenario where all the terminals can communicate with each other using the same radio resource.

Minimal Transmission Power vs. Signal Strength as Distance Estimation for Localization in Wireless Sensor Networks [invited]

Jan Blumenthal (University of Rostock, DE); Frank Reichenbach (University of Rostock, DE); Dirk Timmermann (University of Rostock, DE)

Autonomous localization of nodes in wireless sensor networks is essential to minimize the complex selforganization task and to enhance network lifetime. Known techniques such as distance estimation based on received signal strength are often inaccurate and produce outliers. We propose a new method to measure a distance using the minimal transmission power between a transmitting node and a receiving node. The determined distance is very precise and has a low variance. It is therefore suitable for localization which is exemplary demonstrated for the approximate “Weighted Centroid Localization” algorithm.

Energy Efficiency Analysis of Cooperative Relay Sensor Network [invited]

Lichuan Liu (New Jersey Institute of Technology, US); Zhigang Wang (New Jersey Institute of Technology, US)

This work studies the impact of the network resource constraints on the performance of wireless multi-hop relay sensor networks. The cooperative relay method based on the differential Space-time block code (DSTBC) in sensor network is introduced. The energy consumption is also investigated for different kinds of relay method. Based on the same total energy consumption requirement, we analyze the system performance using M/G/1 queueing system. The performance evaluation show that the cooperative relay scheme can significantly increase the system performance in terms of throughput and end-to-end delay in high SNR environment.

Cooperation in Bandwidth-Constrained Wireless Sensor Networks [invited]

Tony Q.S. Quek (MIT, USA); Moe Z. Win (MIT, USA); Davide Dardari (University of Bologna at Cesena, Italy) 

In this paper, we investigate a binary decentralized detection problem in a dense and randomly deployed wireless sensor network (WSN), whereby the communication channels between the nodes and the fusion center are bandwidth constrained. We consider a scenario in which sensor observations, conditioned on the alternate hypothesis, are independent but not identically distributed across the sensor nodes. We consider two different fusion architectures for such bandwidth-constrained WSNs, namely, the parallel fusion architecture and the cooperative fusion architecture, where each sensor node is restricted to send a 1-bit information to the fusion center. We analyze the effect of varying POI intensity, realistic link models, consensus flooding protocol, network connectivity on the system reliability and average energy consumption for both fusion architectures. We demonstrate that the energy efficiency of cooperative WSNs depends significantly on the POI intensity, node density, flooding energy, network connectivity, and delivery ratio of the consensus flooding protocol.

Capacity Evaluation Framework and Validation of Self-Organized Routing Schemes

Herve Rivano (CNRS - INRIA - UNSA, FR); Fabrice Theoleyre (INSA Lyon - INRIA Rhone Alpes, FR); Fabrice Valois (INSA Lyon, FR)

Assuming a given network topology and a routing protocol, this work is focused on the capacity evaluation of routing protocols based on either a self-organization scheme or a flat approach. To reach this goal, we propose to use linear programming formulation to model radio resource sharing as linear constraints. Four models are detailed to evaluate the capacity of any routing scheme in wireless multihops networks. First, two models of fairness are proposed: either each node has a fair access to the channel, or the fairness is among the radio links. Besides, a pessimistic and an optimistic scenarios of spatial re-utilization of the medium are proposed, yielding a lower bound and an upper bound on the network capacity for each fairness case. Finally, using this model, we provide a comparative analysis of some flat and self-organized routing protocols.

Resilient IPv6 Multicast Address Allocation in Ad Hoc Networks

Janne Lindqvist (Helsinki University of Technology, FI); Antti Ylä-Jääski (Helsinki University of Technology, FI); Jukka Manner (Helsinki University of Technology, FI)

Multicast address allocation in the Internet has been the focus of much research and standardization. However, the multicast address allocation problem has been overlooked in ad hoc networking research. In this paper, we survey approaches to solving the multicast address allocation problem and analyze the security characteristics of the proposals. We show that using random assignment in IPv6 based ad hoc networks for multicast address allocation is more secure and bandwidth efficient than the previous proposals. We use passive listening to obtain network prefixes for autoconfiguring a global multicast address. The ideas presented in this paper are useful for practical deployment of ad hoc networks.

Energy Efficiency in OLSR Protocol

Chiara Taddia (University of Ferrara, IT); Alessandra Giovanardi (University of Ferrara, IT); Gianluca Mazzini (University of Ferrara, IT)

In this paper we study in details the Optimized Link State Routing (OLSR) protocol for ad hoc networks. In particular, we investigate its performance by focusing the attention on its energy efficiency. To have some terms of comparison the performance are compared with those of other routing schemes. Furthermore, to improve the energy efficiency by increasing the network life time, we propose and discuss a power controlled version of OLSR. OLSR Power Controlled provides the optimal paths in terms of minimum power needed to reach the destination, and not in terms of number of hops as in the Classic version. By means of extensive simulations, we show that, in many system conditions, OLSR Power Controlled is able to achieve good energy savings.

Study on an Enhanced Link-Stability based Routing Scheme for Mobile Ad hoc Networks

Wen-fong Wang (National Yunlin University of Science & Technology, TW); Po-Hun Shih (Nat'l Yunlin University of Science & Tech., TW)

In a mobile ad hoc network, each node can move arbitrarily such that its network topology may change frequently. This mobility factor may incur link failure during data packet transmission. The SSA routing protocol can get longer lived routes for ad hoc networks by using a route selection criteria based on signal strength and location stability. It indeed reduces route reconstruction that is caused by the link failure, and thus increases network throughput and decreases overhead. However, SSA is only suitable to the condition of high node density and low mobility, which is the most stable situation for ad hoc networks, due to the route selection strategy in its control algorithm. To compensate SSA for its weakness in the condition of high node density and high mobility and the condition of low node density and low mobility, we proposed an enhanced scheme named as SSA⁺. In this paper, we will describe the mechanisms of SSA⁺ and conduct several simulation experiments to verify and evaluate the performance of our scheme with respect to SSA. Simulation results show that SSA⁺ can effectively reduce the route reconstructions needed in all conditions.

Mobility Metrics for Adaptive Routing

Liang Qin (Carleton University, CA); Thomas Kunz (Carleton University, CA)

Most existing mobile ad hoc routing protocols preset the parameters for the nodes based on some assumed network conditions. Because of the dynamic characteristics of a MANET, network conditions are changing at different points of time. Adaptively adjusting routing behavior by individual nodes will improve the routing protocol performance. In this paper, we mainly focus on the node mobility, and show the correlation between overall performance and node mobility level with simulation results for three different mobility models. We also study the effect of the mobility from point of view of individual nodes. Finally we propose the number of link breakages as a mobility metric, which is mobility model independent, that nodes can use it to monitor the environment changes.

Dynamic Hybrid Multi Routing Protocol For Ad Hoc Wireless Network

Chaorong Peng (Florida Institute of Technology, US); Chang Wen Chen (Florida Institute of Technology, US)

Dynamic Hybrid Multi Routing Protocol (DHMRP) is proposed to overcome re-discovered route via reply path in traditional routing protocol. The protocol utilizes the reply path by establishment of multi routing paths to gain an automatic monitor and repair broken links to reduce the rediscovered route time. And the packets will be delivered by active routes via multi routing path to reduce congestion and traffic “bottlenecks” of Cluster Heads in clustering network so that improving clusters stability due to dynamic topology change so frequently. Performance comparison of DHMRP with  AOMDV using Glomosim simulation shows that DHMRP is able to achieve a lower data delay and route discovery ratio and higher packets deliver ratio.

Joint Network-Channel Coding for the Multiple-Access Relay Channel

Christoph Hausl (Munich University of Technology TUM, DE); Philippe Dupraz (Munich University of Technology, DE)

We propose to use joint network-channel coding based on turbo codes for the multiple-access relay channel. Such a system can be used for the cooperative uplink for two mobile stations to a base station with the help of a relay. We compare the proposed system with a distributed turbo code for the relay channel and with a system which uses separate network-channel coding for the multiple-access relay channel. Simulation results confirm that the systems with network coding for the multiple access relay channel gain cooperative diversity compared to the system with the distributed turbo code for the relay channel. Moreover, the results show that joint network-channel coding outperforms separate network-channel coding. The reason for this is that the redundancy which is contained in the transmission of the relay can be exploited more efficiently with joint network channel coding.

Efficient Data Compression in Wireless Sensor Networks for Civil Infrastructure Health Monitoring

Shengpu Liu (Lehigh University, US); Liang Cheng (Lehigh University, US)

In this paper, we present an efficient sensor data compression process for civil infrastructure health monitoring applications. It integrates lifting scheme wavelet transform (LSWT) and distributed source coding (DSC), which can reduce the raw data size by 1:27 to 1:80 while having a minor effect on the modal parameters identified from the sensor data. We have compared our algorithms with other data compression algorithms for structural health monitoring. Results show that our algorithms can achieve 80% ~ 100% higher compression ratios with the same signal-restoration quality.

A scalable Information dissemination Scheme for Wireless Ad Hoc Networks

Yingjie Li (Troy University, US)

We present the framework of SDSR, a Scalable, efficient, robust and load-balanced Data Storage/Retrieval service for large-scale wireless ad hoc networks. SDSR hashes each data key to normalized geographical coordinates (x,y), which can be seen as a rendezvous point for storing/retrieving the data in a unit grid. SDSR achieves scalability, robustness and load-balancing by partitioning a network into hierarchical grids of increasing sizes and replicating the data item into each grid. The storage location in each grid is determined by scaling the normalized coordinates to the corresponding grid size. SDSR retrieves a data item in the same way as it stores the data item. We show with analysis and simulation that in query dominant, large-scale wireless ad hoc networks, SDSR performs better than existing schemes in terms of energy efficiency, query latency, hotspot usage, and resilience to clustering failures. It scales well when the network size and the number of queries increase.

Query Processing Optimization Through Sample Size and Monitoring Coverage Controlling in Wireless Sensor Networks

Qingchun Ren (Univ of Texas at Arlington, US); Qilian Liang (University of Texas at Arlington, US)

Query processing has been studied extensively in traditional database systems. But few of existed methods can be directly applied to wireless sensor database systems due to their characteristics, such as decentralized nature, limited computational power, imperfect information recorded, and energy scarcity of individual sensor nodes. In this paper, we extend our previous work: quality-guaranteed and energy-efficient algorithm (QGEE) for wireless sensor database systems. We introduce radius of covering disk from point spread function (PSF) aspect and sample size for query quality and energy consumption control. PSF introduces ambiguity into query answers, since the sensitivity of nodes is nonuniform within monitoring region. Sample size determination refers to the process of determining exactly how many samples should be measured in order that the sampling distribution of estimators meets users’ pre-specified target precision. In this paper, we formulate the criteria to determine the optimum radius and sample size according to users’ requirements on query answers. Simulation results demonstrate that the impact of sample size and monitoring coverage on query answers in terms of root mean square error (RMSE).

On the Importance of Modeling the Environment when Analyzing Sensor Networks

Ludovic Samper (France Télécom R&D/ Verimag, FR); Florence Maraninchi (Verimag, FR); Laurent Mounier (Verimag, FR); Erwan Jahier (Verimag/CNRS, FR); Pascal Raymond (Verimag/CNRS, FR)

A sensor network may be considered as a large andcomplex computer system embedded in the physical environment that has some influence on the sensors. The environment is the source of (almost) all activity that occurs in the network. With a simple example modeled in our tool GLONEMO, we show the influence of an environment model that allows to describe correlated stimuli on the set of sensors at a given instant, and also correlations between successive instants.

Code Dissemination in Sensor Networks with MDeluge

Xiao Zheng (UNBC, CA); Behcet Sarikaya (University of Northern British Columbia, CA)

In today’s wireless sensor networks there is a need to improve macro programming of the sensor nodes so that sensor nodes can execute various applications in a flexible manner. There is a need to contribute to macro programming of wireless sensor networks by developing new code dissemination techniques which can disseminate the code into designated sensor nodes. We present a new algorithm called Multicast Deluge (MDeluge) which can be used to disseminate the code image into a designated subnet of a wireless sensor network. MDeluge disseminates code in the sensor network using a tree which is formed when the sensor nodes send code request messages. Micro server keeps the code and sends it based on the requests. MDeluge disseminates binary code as well as capsules of Mate. We extend MDeluge for the sensor networks that are geographically distributed and that have moving nodes. Assuming a grid structured wireless sensor network we present an analysis of various message costs as well as the overall cost of data messages of MDeluge. Simulation of MDeluge shows that MDeluge performs better than Deluge to disseminate the code into designated sensor nodes.

On the Modular Composition of Scalable Application-Layer Multicast Services for Mobile Ad-hoc Networks

Peter Baumung (University of Karlsruhe, DE)

Mobile ad-hoc networks allow wireless devices to freely communicate without the need of any fixed infrastructure. Although many of the emerging applications share the need for multicast communication, their requirements regarding reliable data delivery strongly differ. One single multicast service will thus not provide an acceptable solution for different application and network scenarios. Instead, a multicast service’s flexibility and adaptivity is required in both respects, in order to yield good performance. In this context, application-layer multicast services appear promising: As they rely on so-called overlay networks for data dissemination, they do not require network-wide support and can thus easily be optimized for specific scenarios. We in

this contribution propose a novel architecture for the flexible composition of scalable application-layer multicast services. To do so, we subdivide the latter into different modules, such as transport and overlay routing. By making modules arbitrarily interchangeable, we increase a service’s adaptability and facilitate its development. The service’s scalability is generically ensured, by including our approved technique of Local Broadcast Clustering, which is applicable to arbitrary overlay-multicast algorithms, inside the architecture. As we additionally abstract from a specific network access, developed services can easily be operated and evaluated on top of different network technologies, comprising event-based network simulation software as well as true WLAN-capable devices.

Hybrid Wireless Networks: Applications, Architectures and New Perspectives

Christian Tchepnda (France Telecom R&D, FR); Hasnaa Moustafa (France Telecom R&D, FR); Houda Labiod (ENST, FR)

With the advent and ubiquitous of wireless technology, a wide range of advanced services are expected to be supported including appealing services that currently exist in wired systems. Nevertheless, the resource constraints in wireless environment may render difficulty to realizing all the desirable services. Consequently, an infrastructure with high data rate is necessary to complement the resource constraints and to act as anchor points linking mobile nodes to other fixed networks as the Internet. Hybrid wireless networks have emerged as a promising solution, allowing mobile clients to achieve higher performance and service access in a seamless manner independent of their existence in Wireless LAN (WLAN) communication range. In this paper we address the benefits of hybrid wireless networks, showing their possible applications and presenting a classification for their emerging

architectures. Also, we identify the research challenge arising from the problem of applying the grid computing concept in such hybrid wireless environment, showing the expected benefits from the aggregated fixed-mobile capacity. Finally, we propose our vision for a potential architectural model, which is expected to provide useful services by the network operator or the service provider in such a hybrid environment.

A P2P approach to Streaming Multimedia Contents in a E-learning Oriented Platform

Andrea Odorizzi (University of Ferrara, IT); Gianluca Mazzini (University of Ferrara, IT)

Abstract—In this paper a new distributed platform is proposed. The aim of the platform is providing a very simple environment which is able to share the media required in a synchronous e-learning session or in a video conference, i.e., video and audio captured streams, slide sequences and the mouse movement when the mouse pointer is over a shared slide. By using a source routing strategy every peer transmits the captured streams over one or multiple paths that reach all the multimedia session participants. With this distributed approach we are able to increase the number of participants, to avoid limitations due to the client-server bottleneck and to reduce the network load  per participant in comparison to a client-server architecture with unicast communications. The proposed structure also integrates and takes advantage of the local multicast network infrastructures.

BENCHManet: An Evaluation Framework for Service Discovery Protocols in MANET

Mohamed Abou El Saoud (Carleton University, CA); Samy Mahmoud (Carleton University, Ottawa, Canada, CA); Thomas Kunz (Carleton University, CA)

In the world of wireless ad-hoc networking, the problem of service discovery is essential and important in order to detect and access services between mobile computers. This has hence led to the advent of numerous Service Discovery Protocols (SDPs). We recognize the need for a legitimate framework for the qualitative and quantitative evaluation of SDPs in mobile networking contexts such Mobile Ad Hoc Networks (MANETs). This paper presents Benchmark for MANET (BENCHManet), an initiative development of a comprehensive and sophisticated benchmark composed of reference tests, each of which reflects the configuration found in various realistic MANET applications. The presented benchmark allows for a more practical and comprehensive evaluation, as well as a fair comparison of SDPs.

Cognitive Adaptive Radio Teams

Richard Lau (Telcordia Technologies, US)

Cognitive Adaptive Radio Teams (CART) is a new platform developed by our group in support of collaborative mapping of complex communications-

challenged environments, for example in support of search and rescue operations in environments lacking an adequate communications infrastructure. Experience during the 9/11 terrorist attacks, Asian Tsunami, Kashmir Earthquake, and post-Katrina Gulf Coast make it clear that rescue workers cannot count upon computer networks or even cell telephone support in the immediate aftermath of such events. Similarly, military urban warfare operations must also be conducted in locations lacking communication infrastructure. CART combines state-of-the-art ad-hoc networking technology with machine learning and prediction algorithms to offer new capabilities under these very difficult conditions.

Effect of Ad Hoc Routing Protocols on TCP Performance within MANETs [invited]

Alaa Seddik-Ghaleb (Institut
d’Informatique d’Entreprise, France); Yacine Ghamri-Doudane(Institut
d’Informatique d’Entreprise, France); Sidi-Mohammed Senouci (France Telecom, France)

TCP was mainly developed to be deployed within wired networks. Recently, many researches have studied its performance within Mobile Ad hoc Networks (MANETs). These researches found that TCP performance are highly influenced by the characteristics of such networks. This is due to TCP’s reliability mechanism and its inability to discriminate the packet loss cause. Indeed, unlike wired networks, where packet loss is mainly caused by network congestion, in MANETs we could have many other reasons to lose a data packet. However, TCP considers that all packet losses are due to network congestion. This enforces TCP to be aggressive in front of certain types of loss. Packet losses in MANETs can be either related to wireless communication environment (i.e. the effect of fading, interference, multipath routing, etc.) or to the dynamic nature of such networks (i.e. link failures, network partitioning). This latter could be due to the node mobility or to the node battery depletion. This could lead to frequent route re-computation within the network. In this work, we intend to study the effect of ad hoc routing protocols on TCP performance (energy consumption and average goodput1) within MANETs. We consider studying different types of ad hoc routing protocols having different characteristics: reactive vs. proactive, distance vector vs. link state, and source routing. Our study results show that; DSDV as a proactive distance vector routing protocol leads to most accepted TCP performance results and this is confirmed at different mobility levels.

Cooperative Routing [invited]

Cristina Comaniciu (Stevens Institute of Technology, US)

not available

Queuing Delay and Achievable Throughput in Random Access Wireless Ad Hoc Networks [invited]

Nabhendra Bisnik (Rensselaer Polytechnic Institute, US); Alhussein Abouzeid (Rensselaer Polytechnic Institute, US)

In this paper we focus on characterizing the average end-to-end delay and maximum achievable per-node throughput in random access multihop wireless ad hoc networks with stationary nodes. We present an analytical model that takes into account the number of nodes, the random packet arrival process, the extent of locality of traffic, and the back off and collision avoidance mechanisms of random access MAC. We model random access multihop wireless networks as open G/G/1 queuing networks and use diffusion approximation to evaluate closed form expressions for the average end-to-end delay. The mean service time of nodes is derived and used to obtain the maximum achievable per-node throughput. The analytical results obtained here from the queuing network analysis are discussed with regard to similarities and differences from the well established information-theoretic results on throughput and delay scaling laws in ad hoc networks. We also investigate the extent of deviation of delay and achievable throughput in a real world network from the analytical results presented in this paper. We perform extensive simulations and verify that the analytical results closely match the results obtained from simulations.

Efficient Scheduling of Multi-User Multi-Antenna Systems [invited]

Phil Whiting (Bell Labs Lucent Technologies, US)

not available

Throughput benefits of network coding [invited]

Emina Soljanin (Bell Labs Lucent Technologies, US)

not available

A Zone based energy efficient protocol for information collection in wireless sensor network

Siddhartha Satapathy (Tezpur University, IN); Rakesh Tripathi (Tezpur University, IN); Nitul Dutta (Tezpur University, IN)

Limited battery powers of sensor nodes in Wireless Sensor Networks (WSNs) demand for routing protocols that consume least possible amount of energy. There is some fixed amount of energy cost in the electronics when transmitting or receiving a packet and a variable cost when transmitting a packet which depends on the distance of transmission. If each node transmits its sensed data directly to the base station, then it will deplete its power quickly. In this paper, we propose a position aware multi-zone routing protocol for gathering of data from the sensor field. Our protocol divide the sensor field in to different zones and construct a chain like path of nodes in a greedy way for gathering information. From simulation results we found that our proposed protocol can achieve higher efficiency in terms of total energy consumed per round of communication and hence longer life to the system.

Towards Efficient Temperature Temperature Monitoring and Controlling in Large Grain Depot

Bin Xu (Zhejiang Gongshang University, CN)

Temperature sensors are widely used in monitoring the environment temperature of large grain depots. Efficiently temperature monitoring and controlling is required so as to handle the large amount of temperature sensors. A new protocol is proposed to monitor the temperature other than check the temperature per node. Warning window mechanism used in the protocol is also described. The results from the industry showed large benefit of the suggested protocol.

A New Solution Based on Monte Carlo to Wireless Sensor Network Density Control Problem

Jia Yufu (Huazhong University of Science and Technology, CN)

An effective approach for energy conservation in wireless sensor networks is to schedule sleep intervals for extraneous nodes, while the remaining nodes stay active to provide continuous service. In this paper, we proposed a new scheme based on Monte Carlo algorithm to test whether the nodes deployed in interested region are redundant or not. The computational complexity is only O(n). It also established the coverage collision detection and back-off mechanism applied in the wireless sensor network. The simulation results show that the system can cover all the interested area with least nodes and the coverage void will not appear during the course of state-transition. The coverage collision detection and back-off mechanism proposed in this article can be applied when the nodes both have synchronous and asynchronous mechanism. It also provides a stable stage with the length of the time can be adjusted.

Adaptive Multiuser Interference Cancellation for DS-UWB

Jiao Shengcai (Beijing University of Posts and Telecommunications, CN)

In this paper, we propose an adaptive multi-user interference cancellation for Direct Sequence Ultra-Wideband (DS-UWB) communications. Much of the published research to date has focused primarily to the multi-user detection based on conventional CDMA systems, however, those items have some matters such as slowly convergence rate and complexly computation. The proposed algorithm is a parallel iterative interference cancellation algorithm, and makes use of MMSE optimum filter in each user, at the same time, it takes the other users as the interference. The simulation result shows that it has a faster convergence rate.

Rate Control to Reduce Bioeffects in Wireless Biomedical Sensor Networks

Hl Ren (CUHK, HK)

During the course of physiological information monitoring by wireless biomedical sensor networks, adverse biological effects will be caused by wireless radio frequency radiation, especially for long term, intensive and close inspection. This paper is concerned with bioeffect metric to evaluate the performance of wireless biosensor networks in terms of health effect consideration, and a price-based rate control algorithm to reduce the bioeffect. This paper first investigates the bioeffects caused by radiofrequency transmission of sensor node, including thermal effects and athermal effects. The bioeffects model is studied in both near-field and far-field, in relation to Specific Absorption Rate (SAR). The main contribution of this work is that a normalized bioeffect metric, equivalent Coefficient-of-Absorption-and-Bioeffects (CAB), is derived to evaluate and design the communication protocols for wireless biosensor networks. After identifying the factors that can reduce the adverse health effects in the communication system we present a bioeffect aware rate control algorithm for the system.

LLM: Low Latency MAC Protocol for Wireless Sensor Network

Atanu Roy Chowdhury (IIT-Guwahati, IN); Sumeet Parmar (Indian Institute of Technology, Guwahati, IN); Sukumar Nandi (Indian Institute of Technology, Guwahati, IN)

Existing protocols for medium access in Wireless Sensor Networks opt for staggered wakeup scheduling among clusters of nodes. However intra-cluster contention and interference has remained an unaddressed issue. In this work we propose PELLMAC: Power Efficient and Low Latency MAC for Wireless Sensor Networks, a schema that addresses node scheduling for channel access. By limiting contention between adjacent branches of the data gathering tree, we are able to reduce the latency of the network, as well as optimize energy utilization. Simulation results, in accordance with our claims, show that PELLMAC enhances performance in energy savings, latency and delivery ratio.

Topology Discovering Mechanism for Power Saving in Ad-hoc Wireless Networks

Arwa Zabian (Irbid National University, JO)

Power saving is an important issue in ad-hoc wireless networks, where no centralized communication is issued. Each node works as router to the others to allow the network connectivity. So, each node consumes parts of its energy in a forwarding others packets. In this paper we propose a self adjustment power saving mechanism for routing in ad-hoc wireless networks that results in significant power saving for all the network. Our mechanism is based on TDA (topology discovering algorithm)[11] in which each node knows who are the active nodes in a fraction of the network. By determined simulation experiments, our simulation results show that in a topology like that constructed by TDA, the power consumption in routing is independent on the network size and is related only to the height of the tree built by the algorithm and to the packet size.

Application of Video Sensor Networks in ITS

Kai Zhou (Tongji University, CN)

This paper proposes a new data link routing protocol, which realizes more efficient transmitting of video information and meets the requirement of traffic organization and data collection. It takes the traffic circumstance into consideration and synthesizes the two classic protocols, LEACH and PEGASIS. In order to realize the visual management of the traffic network, we allocate sensors along the roads, so as to introduce a link configuration.  We also consider the usage of cluster for time saving. This paper focuses on the comparison of the three protocols, LEACH, PEGASIS and the newly proposed algorithm. The simulation results indicate that our algorithm is much better than LEACH in power consumption and smarter than PEGASIS in network latency. Furthermore, the data collected by applying this protocol are the most suitable for the further work in ITS data analysis.

Clustering Ad Hoc Networks: Schemes and Classifications

Dali Wei (University of Cape Town, ZA); Anthony Chan (University of Cape Town, ZA)

Many clustering schemes have been proposed for different ad hoc networks and play an important role in self organizing them. A systematic classification of these clustering schemes enables one to better understand and make improvements. This paper surveys clustering schemes and classifies them into ad hoc sensor network clustering schemes and mobile ad hoc network clustering schemes. In sensor networks, the energy stored in the network nodes is limited and usually infeasible to recharge; the clustering schemes for these networks therefore aim at maximizing the energy efficiency. In mobile ad hoc networks, the movement of the network nodes may quickly change the topology resulting in the increase of the overhead message in topology maintenance; the clustering schemes for mobile ad hoc networks therefore aim at handling topology maintenance, managing node movement or reducing overhead.

Performance Analysis of Multipath Data Transmission in Multihop Ad Hoc Networks

Li Zhao (Washington State University, US); Jose Delgado (Washington State University, US)

Data transmission in ad hoc networks involves interactions between MAC-layer protocol and data forwarding along network-layer paths. These interactions have been shown to have significant effect on system throughput and source queue characteristics. In this paper, multipath data transmission is studied and analyzed based on the DCF in IEEE 802.11 MAC protocols. Analytical models are developed to demonstrate the frame service time and the queue characteristics in the source station under unsaturated conditions for two frame arrival processes (Poisson and deterministic) and two packet generation processes (round robin and batch). The throughput in the multipath multihop system under saturated conditions is investigated and a bound of it is derived. These models are all validated by means of simulation under various scenarios.

A MAC Protocol Equipped by a Novel Transmission Scheduling Algorithm for Wireless LANs

Kaveh Ghaboosi (Sharif University of Technology, IR); Babak Hossein Khalaj (Sharif University of Technology, IR)

Hidden-terminal is one of the main problems in ad hoc wireless networks. In addition, there are scenarios where the desired destination is located in the range of other transmitters, so that the efforts on setting up communication with this terminal will fail due to collisions that may occur between transmitted control frames and undesired received control and data frames. This phenomenon becomes a bottleneck when most of data transmissions experience packet fragmentation. In such scenarios, the desired destination becomes unreachable during the data transfer of neighboring nodes. Using the same PHY of IEEE 802.11 and making slight modifications in its MAC, a new medium access control scheme equipped by a novel transmission scheduling algorithm is presented to address such problems. The performance of the proposed approach is compared with earlier schemes through simulation-based evaluations, showing performance enhancement due to better handling of unreachability issues in the proposed MAC scheme.

Power Efficient and Low Latency MAC for Wireless Sensor Networks

Atanu Roy Chowdhury (IIT-Guwahati, IN); Sumeet Parmar (Indian Institute of Technology, Guwahati, IN); Sukumar Nandi (Indian Institute of Technology, Guwahati, IN)

Existing protocols for medium access in Wireless Sensor Networks opt for staggered wakeup scheduling among clusters of nodes. However intra-cluster contention and interference has remained an unaddressed issue. In this work we propose PELLMAC: Power Efficient and Low Latency MAC for Wireless Sensor Networks, a schema that addresses node scheduling for channel access. By limiting contention between adjacent branches of the data gathering tree, we are able to reduce the latency of the network, as well as optimize energy utilization. Simulation results, in accordance with our claims, show that PELLMAC enhances performance in energy savings, latency and delivery ratio.

Data-Sink Based Energy-Efficient Algorithm for Ad Hoc Sensor Networks

Dali Wei (University of Cape Town, ZA); Anthony Chan (University of Cape Town, ZA)

Scheduling schemes play an important role in energy saving for high density ad hoc sensor networks. This paper proposes an energy distributed scheduling algorithm to maximize the energy efficiency for a sensor network in which all data are sent to a data sink for further analysis. Here, the network is divided into many circular layers with the data sink in the center. This algorithm 1) reduces both flooding and delay in reactive route discovery by designing a directional route from the source sensor node to the data sink, and 2) maintains the connectivity of the entire network by distributing power consumption throughout the entire network so that all circular layers have the same lifetime and all energy in the network can be efficiently used. We also modify the Geographical Adaptive Fidelity (GAF) to compare with our algorithm. Simulation results show that the proposed algorithm can extend 21% lifetime of the network compared with the modified GAF algorithm.

RF-Based Location System using cooperative calibration

Ricardo Reghelin (Universidade Federal de Santa Catarina, BR); Antonio Augusto Fröhlich (Universidade Federal de Santa Catarina, BR)

This paper studies the problem of determining the location of nodes in a wireless sensor network. We describe a fully decentralized algorithm called HECOPS where every node estimates its own position after interactions with other nodes. Only a limited fraction of nodes have knowledge of their position coordinates, however any node can be selected as a reference. We propose a ranking system to determine the reliability of each estimated position. This leads to a novel approach for position calculation that uses fewer but more reliable landmarks, thus reducing data communication and limiting error propagation. Heuristics are used to reduce the effects of measurement errors, including a scheme to calibrate range measurements by comparing, whenever possible, the estimated distance with the actual distance between a pair of nodes. Experiments demonstrate that the algorithm is superior to a previously proposed method in terms of its ability to compute correct coordinates under a wider variety of conditions and its robustness to measurement errors.

A Comprehensive Comparison of Routing Protocols for Large-Scale Wireless MANETs

Ioannis Broustis; Gentian Jakllari; Thomas Repantis; Mart Molle

Efficient routing protocols can provide significant benefits to mobile ad hoc networks, in terms of both performance and reliability. Many routing protocols for such networks have been proposed so far. Amongst the most popular ones are Dynamic Source Routing (DSR), Ad hoc On-demand Distance Vector (AODV), Temporally-Ordered Routing Algorithm (TORA) and Location-Aided Routing (LAR). Despite the popularity of those protocols, research efforts have not focused in evaluating their performance when applied to large-scale wireless networks. Such networks are comprised of hundreds of nodes, connected via long routes. This greatly affects the network efficiency, since it necessitates frequent exchange of routing information. In this paper we present our observations regarding the behavior of the above protocols, in large-scale mobile ad hoc networks (MANETs). We consider wireless mobile terminals spread over a large geographical area, and we perform extensive simulations, using the QualNet and NS-2 simulators. The results of the simulations yield some interesting conclusions: AODV suffers in terms of packet delivery fraction (PDF) but scales very well in terms of end-to-end delay. DSR on the other hand scales well in terms of packet delivery fraction but suffers an important increase of end-to-end delay, as compared to its performance achieved in smallscale topologies. Also, the effect of maximum connections is severe on TORA, which seems unable to route large amounts of traffic. LAR, seems to scale very well, in terms of all metrics employed.

Doughnut Effect in Wireless Sensor Network and its Solution

Kumar Padmanabh (Indian Institute of Technology, Kharagpur, India., IN); Rajarshi Roy (Indian Institute of Technology, Kharagpur, IN)

The sensor nodes in a network are connected to the outer world via a base station. Base stations (BS) have some back up power and it is not suppose to fail due to shortage of battery power. The nodes which are away from the base station communicate to it via the nodes which are in proximity of BS. Thus the nodes which are nearer to BS have additional communication responsibilities of forwarding data of distant nodes. Thus the nodes which are in proximity of BS will run out of battery very soon and create bottleneck for communication. In this paper we have proposed that if the density of sensor nodes increases as we move towards base station this effect can be minimized. We found the exact density of the sensor nodes at a particular distance from BS to avoid bottleneck phenomenon around it. We have considered the real life scenario (i) sensor nodes are dropped from the aeroplane with possible error in its position from predetermined coordinates and (ii) Nodes generates data only when there is an event of interest with a given probability of occurrence. The main contribution of this paper with our proposed strategy is lifetime offered per unit cost of deployment is almost double.

A Probabilistic Energy-Efficient Routing (PEER) Scheme for Ad-hoc Sensor Networks

Kai Chen (University of Science and Technology of China, CN); Yang Qin (University of Science and Technology of China, CN); Fan Jiang (University of Science and Technology of China, CN); Zongyao Tang (University of Science & Technology of China, CN)

Ad-hoc wireless sensor networks consist of small nodes with sensing, computing, and wireless communicating capabilities. Energy deficiency is a key problem of these kinds of networks. Many routing, power management, and data dissemination protocols have been specifically designed for them where energy awareness is a chief design issue. This paper proposes a new probabilistic agent-based energy efficient routing strategy (PEER). In contrast to the earlier work that focus on energy-aware routing, PEER takes into account both total cost and individual residual energy of the whole path statistically (path-based) when selecting the next hop, i.e. each intermediate node chooses its next hop node based on the statistical path information from that node to the sink. We show through analysis and simulations that PEER can prolong the network survivability, shorten the average packet delay, and hence outperform all the existing routing schemes. Moreover, we conjecture that the coefficient ρ in PEER may be intelligently adjusted to fit the situation of the volatile networks, thus we make further investigation into it and achieve the intending results.

Performance Evaluation of Secure On Demand Routing Protocols for Mobile Ad hoc Networks

Junaid Arshad (IIUI, PK)

for mobility wireless or mobile networks emerged to replace the wired networks. This new generation of networks is different from the earlier one in many aspects like network infrastructure, resources and routing protocols, routing devices etc. These networks are bandwidth and resource constrained with no network infrastructure and dedicated routing devices. Moreover, every node in such networks has to take care of its routing module itself. These characteristics become reasons for the importance of security in mobile ad-hoc networks as there is very high probability of attacks in such networks. Some work has been done to compare different protocols on basis of security but keeping in view the resource limitations in such networks, evaluation based on networking context is also important.

We evaluate the overall performance overhead associated with secure routing protocols for mobile ad-hoc networks (MANETs).We implement the Secure Ad-hoc on-Demand Distance Vector routing protocol (SAODV) extensions with AODV[1] in the Network Simulator 2 (NS-2) and use the Monarch Project[2] implementation of Ariadne for our evaluation purpose. We try to figure out the amount of extra work a mobile node has to do in order to operate securely.